In a traditional communication system using encoding and modulation, output data of an encoding module typically results from puncturing or repeating a mother code. If a required code rate is lower than a rate of the mother code, then it is typically repeated. On the contrary, if the required code rate is higher than the rate of the mother code, then it is typically punctured.
FIG. 1 illustrates a schematic diagram of an encoding module using puncturing and/or repetition. In FIG. 1, information is encoded by the encoding module to obtain a mother code at a code rate of 1/3. The mother code is composed of information data and parity data. In the example of FIG. 1, the parity data is composed of parity data 1 and parity data 2. As illustrated in FIG. 1, the last four bits are a repetition of the first four bits and referred to a repetition code in the case of using repetition and requiring a code rate of 1/4. In this case of repetition, the mother code and the repetition code serve together as transmission data. Only the first eight bits of data of the mother code is transmitted in the case of using puncturing and requiring a code rate of 1/2.
As can be apparent from currently published articles and patents, a majority of solutions concern a design of a puncturing pattern for the approach of puncturing. For the approach of repeating, a typical solution is to select data of a mother code as a repetition code through loop buffering and then modulate output data of an encoding module in a pre-selected modulation scheme. These methods can be found in, for example, “3GPP TS 36.212 v8.4.0 (2008-09)-3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (Release 8)” and U.S. patent application Publication No. US2008260067A1, by Christian Wengerter et al, entitled “Bit Reliability Equalization By Modulation Switching For HARQ”. The contents of these documents are incorporated here by reference.
However, an improved data transmission method and apparatus is still desired at present to reduce the complexity of demodulation at a receiver while improving the performance of reception at a communication system.